Time-Division Driving Type Touch Sensing Device and Method for Driving the Same

ABSTRACT

A touch sensing display device supporting a pixel driving period and a touch driving period in each frame period. The device comprises a display panel having data lines and touch sensing lines, the data lines coupled to pixels of the display panel. A data driving circuit drives data signals onto the data lines during the pixel driving period of the frame period. A touch readout circuit generates touch data of signals of the touch sensing lines during the touch driving period of the frame period, the touch driving period distinct of the pixel driving period. A supply voltage of the data driving circuit can be cut off during the touch driving period, and a supply voltage of the touch readout circuit can be cut off during the pixel driving period.

This application is a continuation application under 35 U.S.C. §120 ofU.S. patent application Ser. No. 14/711,561 filed on May 13, 2015, whichclaims the benefit of Korea Patent Application No. 10-2014-0065874 filedon May 30, 2014, all of which are incorporated herein by reference forall purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention relate to a time-division driving typetouch sensing device and a method for driving the same.

2. Discussion of the Related Art

User interfaces (UI) are configured so that users are able tocommunicate with various electronic devices and thus can easily andcomfortably control the electronic devices as they desire. Examples of auser interface include a keypad, a keyboard, a mouse, an on-screendisplay (OSD), and a remote controller having an infrared communicationfunction or a radio frequency (RF) communication function. Userinterface technology has continuously expanded to increase usability andhandling convenience. The user interfaces have been recently developedto include touch UI, voice recognition UI, 3D UI, etc.

The touch UI has been used in mobile devices. The touch UI isimplemented by forming a touch screen on the screen of a displayelement. The touch screen may be implemented as a capacitive touchscreen. The touch screen has capacitive touch sensors sensing changes(i.e., changes in charges of the touch sensor) in a capacitancegenerated when the user touches the touch sensor with his or her fingeror a conductive material, and thus detects a touch input.

A touch sensing device having a touch screen integrated type displayelement senses changes in capacitance of touch sensors before and aftera touch (or proximity) operation and decides whether or not there is atouch (or proximity) input using a conductive material. Further, thetouch sensing device finds out a position of the touch input when thereis the touch input. In the touch sensing device, one frame period may betime-divided into a pixel driving period P1, in which data of an inputimage is applied to pixels of the display element, and a touch sensordriving period P2, in which the touch sensors are driven, as shown inFIG. 1.

The time-division driving type touch sensing device has a problem of anincrease in power consumption due to power consumed by circuit blocks,that are not used in the driving periods P1 and P2.

The time-division driving type touch sensing device may include a sourcedriver integrated circuit (IC), that normally operates only during thepixel driving period P1, and a readout IC, that normally operates onlyduring the touch sensor driving period P2. The source driver IC does notneed to operate during the touch sensor driving period P2 and thus isnot used during the touch sensor driving period P2. On the other hand,the readout IC does not need to operate during the pixel driving periodP1 and thus is not used during the pixel driving period P1.

However, during operation of the time-division driving type touchsensing device, driving power is continuously supplied to each of thesource driver IC and the readout IC. Thus, unnecessary current flowsinto the unused readout IC during the pixel driving period P1, and alsounnecessary current flows into the unused source driver IC during thetouch sensor driving period P2. Hence, the power consumption of thetime-division driving type touch sensing device increases.

SUMMARY OF THE INVENTION

Accordingly, embodiments of the invention provide a time-divisiondriving type touch sensing device and a method for driving the samecapable of reducing power consumption.

In one embodiment, a touch sensing display device supporting a pixeldriving period and a touch driving period in each frame period isdisclosed. The device comprises a display panel having data lines andtouch sensing lines, the data lines coupled to pixels of the displaypanel; a data driving circuit to drive data signals onto the data linesduring the pixel driving period of the frame period, the data drivingcircuit powered by a first supply voltage; a touch readout circuit togenerate touch data of signals of the touch sensing lines during thetouch driving period of the frame period, the touch driving perioddistinct from the pixel driving period; and a first power controller tocut off the first supply voltage of the data driving circuit during thetouch driving period of the frame period.

The touch readout circuit can be powered by a second supply voltage. Thedisplay also comprises a second power controller to cut off the secondsupply voltage of the touch readout circuit during the pixel drivingperiod of the frame period.

The display device can comprise a timing controller to generate a shutdown control signal. The first power controller cuts off the firstsupply voltage of the data driving circuit responsive to the shut downcontrol signal. The timing controller can also generate a wake upsignal, and the first power controller applies the first supply voltageto the data driving circuit responsive to the wake up signal.

The first supply voltage that is cut off during the touch driving periodof the frame period can be a supply voltage for an analog portion of thedata driving circuit. Alternatively, the first supply voltage that iscut off during the touch driving period of the frame period can be asupply voltage for a digital portion of the data driving circuit.

The data driving circuit can comprise a digital-to-analog converter(DAC) to convert video data into analog data voltages; and an outputcircuit to drive the analog data voltages onto the data lines. The firstsupply voltage that is cut off during the touch driving period of theframe period is a supply voltage for the output circuit but not the DAC.

The touch sensing display device can comprise a common electrodepatterns corresponding to the pixels, the common electrode patternsdriven with at least one touch driving signal during the touch drivingperiod and driven with a common voltage during the pixel driving period.

In another embodiment, a touch sensing display device supporting a pixeldriving period and a touch driving period in each frame period isdisclosed. The device comprises a display panel having data lines andtouch sensing lines, the data lines coupled to pixels of the displaypanel; a data driving circuit to drive data voltages onto the data linesduring the pixel driving period of the frame period; a touch readoutcircuit to generate touch data of signals of the touch sensing linesduring the touch driving period of the frame period, the touch drivingperiod distinct from the pixel driving period, the touch readout circuitpowered by a first supply voltage; and a first power controller to cutoff the first supply voltage of the touch readout circuit during thepixel driving period of the frame period.

The data driving circuit can be powered by a second supply voltage, andthe display device further comprises a second power controller to cutoff the second supply voltage of the data driving circuit during thetouch driving period of the frame period.

The display device can comprise a timing controller to generate a timingdivision synchronization signal indicative of whether the frame periodis in the pixel driving period or the touch driving period. The firstpower controller cuts off the first supply voltage of the touch readoutcircuit responsive to the timing division synchronization signal.

The first supply voltage that is cut off during the pixel driving periodof the frame period can be a supply voltage for an analog portion of thetouch readout circuit. Alternatively, the first supply voltage that iscut off during the pixel driving period of the frame period is a supplyvoltage for a digital portion of the touch readout circuit.

The display device can comprise common electrode patterns correspondingto the pixels, the common electrode patterns driven with at least onetouch driving signal during the touch driving period and driven with acommon voltage during the pixel driving period.

In a further embodiment, a method of operation in a touch sensingdisplay device is disclosed. The method can comprise driving, by a datadriving circuit powered by a first supply voltage, data voltages ontodata lines of a display panel during a pixel driving period of a frameperiod, the data lines coupled to pixels of the display panel;generating touch data from signals of touch sensing lines of the displaypanel during a touch driving period of the frame period, the touchdriving period distinct from the pixel driving period; and cutting offthe first supply voltage of the data driving circuit during the touchdriving period of the frame period.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 shows an example where one frame period is time-divided into apixel driving period and a touch sensor driving period;

FIG. 2 is a block diagram of a time-division driving type touch sensingdevice according to an exemplary embodiment of the invention;

FIG. 3 shows an example of touch sensors embedded in a pixel array;

FIG. 4 shows another example of touch sensors embedded in a pixel array;

FIG. 5 is a waveform diagram to operate a touch sensor shown in FIG. 4;

FIG. 6 shows a multiplexer formed between a touch sensor driving circuitand touch sensors;

FIG. 7 is a waveform diagram showing an example of a time-divisiondriving method of a pixel driving period and a touch sensor drivingperiod;

FIG. 8 illustrates a concept for reducing power consumption of atime-division driving type touch sensing device according to anexemplary embodiment of the invention;

FIG. 9 shows EPI (clock embedded) lines connected between a timingcontroller and source driver integrated circuits (ICs);

FIG. 10 shows a timing controller and a clock recovery circuit of asource driver IC;

FIG. 11 is a waveform diagram showing an EPI interface protocol forsignal transmission between a timing controller and source driver ICs;

FIG. 12 is a waveform diagram showing an EPI interface signaltransmitted to source driver ICs during a horizontal blank period;

FIG. 13 shows a first driving power controller for controlling drivingpower of a readout integrated circuit (IC);

FIG. 14 shows a second driving power controller for controlling drivingpower of a source driver IC; and

FIG. 15 shows an example where a driving power control signal is encodedto an EPI data packet.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to embodiments of the invention,examples of which are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts.

A touch sensing device according to an exemplary embodiment of theinvention includes a touch screen integrated type display element. Thedisplay element may be implemented based on a flat panel display, suchas a liquid crystal display (LCD), an organic light emitting diode(OLED) display, an electrophoresis display (EPD), and a plasma displaypanel (PDP). In the following description, the embodiment of theinvention will be described using the liquid crystal display as anexample of the flat panel display. Other flat panel displays may beused.

A touch screen according to the embodiment of the invention includestouch sensors, and the touch sensors may be embedded in a pixel array.The touch sensors may be implemented as capacitive touch sensors whichsense a touch input based on changes in a capacitance before and after atouch operation. The capacitive touch sensors may be classified intomutual capacitive touch sensors and self capacitive touch sensors. Asshown in FIG. 3, the mutual capacitive touch sensor is formed betweentwo conductor lines perpendicular to each other. As shown in FIG. 4, theself capacitive touch sensor is formed along conductor lines of a singlelayer formed in one direction.

Referring to FIGS. 2 to 7, a touch sensor embedded type touch sensingdevice according to the embodiment of the invention includes a displaypanel 100, display driving circuits 202, 204, and 104, touch sensordriving circuits 302, 304, 306, and 308, and the like.

A thin film transistor (TFT) array substrate of the display panel 100includes a plurality of data lines D1 to Dm (where m is a positiveinteger), a plurality of gate lines G1 to Gn (where n is a positiveinteger) crossing the data lines D1 to Dm, a plurality of pixel TFTsformed at crossings of the data lines D1 to Dm and the gate lines G1 toGn and that are coupled to these lines, a plurality of pixel electrodes11 which are connected to the data lines D1 to Dm through the pixel TFTsand are charged to a data voltage, a plurality of common electrodes towhich a common voltage Vcom is supplied, a plurality of touch sensors,and the like. The TFT array substrate further includes storagecapacitors (not shown). The storage capacitor is connected to the pixelelectrode 11 and holds a voltage of a liquid crystal cell.

As shown in FIG. 7, in the touch sensing device according to theembodiment of the invention, one frame period may be time-divided into apixel driving period P1, in which data of an input image is applied topixels of the display element by driving data voltages onto the datalines D1-Dn, and a touch sensor driving period P2, in which the touchsensors are driven and touch signals are converted into touch data.Pixel driving period P1 is distinct in time from touch sensor drivingperiod P2. In this instance, video data corresponding to one frame isapplied to all of the pixels during the pixel driving period P1, and allof touch driving lines are driven during the touch sensor driving periodP2.

The touch sensors according to the embodiment of the invention may beimplemented as mutual capacitive touch sensors as shown in FIG. 3, ormay be implemented as self capacitive touch sensors as shown in FIGS. 4to 6.

The mutual capacitive touch sensors include touch driving Tx lines T1 toTj (where ‘j’ is a positive integer less than n), touch sensing Rx linesR1 to Ri (where ‘i’ is a positive integer less than m), mutualcapacitances formed at crossings of the Tx lines T1 to Tj and the Rxlines R1 to Ri, and the like. The mutual capacitive touch sensors havingan electrode structure shown in FIG. 3 may be embedded in the pixelarray. The Tx lines T1 to Tj include common electrode division patternsT11 to T23 and link patterns L11 to L22. The first Tx line T1 includesthe plurality of common electrode division patterns T11 to T13 which areconnected along a horizontal direction via the link patterns L11 andL12. The second Tx line T2 includes the plurality of common electrodedivision patterns T21 to T23 which are connected along the horizontaldirection via the link patterns L21 and L22. The size of each of thecommon electrode division patterns T11 to T23 may be patterned to belarger than the pixel size, so that each common electrode divisionpattern includes two or more pixel areas. Each of the common electrodedivision patterns T11 to T23 may be formed of a transparent conductivematerial such as indium tin oxide (ITO). The link patterns L11 to L22electrically connect the common electrode division patterns T11 to T23which are adjacent to each other in the horizontal direction. The mutualcapacitive touch sensors may have structures other than the structureshown in FIG. 3. For example, the mutual capacitive touch sensorsembedded in the pixel array may be manufactured using the structuredisclosed in Korean Patent Application No. 10-2012-0143228 (Dec. 11,2012) owned by the present applicant, and which are hereby incorporatedby reference in their entirety.

The Tx lines T1 to Tj and the Rx lines R1 to Ri are connected to thecommon electrodes and supply the common voltage Vcom to the commonelectrodes during the pixel driving period P1. During the touch sensordriving period P2, a touch driving signal for driving the touch sensorsis supplied to the Tx lines T1 to Tj, and the Rx lines R1 to Ri receivea touch sensing signal output of the touch sensors in synchronizationwith the driving signal.

The circuitry within the touch sensor circuit 304 may also be dividedinto different power domains (not shown). A primary power domainincludes circuitry to provide the common voltage Vcom to the Rx linesduring the pixel driving period P1. A secondary power domain includescircuitry to receive and convert the touch sensing signals to touch dataduring the touch sensor driving period P2. The secondary power domain ispowered by a supply voltage VDD or VCC, and the supply voltage VDD orVCC can be selectively cut off to reduce power consumption in the touchsensor circuit 304.

Referring to FIGS. 4 to 6, the self capacitive touch sensors may includecommon electrode division patterns COM1 to COMn. Each of the commonelectrode division patterns COM1 to COMn may be formed of indium tinoxide (ITO) and may be patterned to be larger than the pixel. As shownin FIG. 4, the touch sensor driving circuit 308 may be individuallyconnected to the common electrode division patterns COM1 to COMn throughsensing lines S1 to Sn. The touch sensor driving circuit 308 may supplythe common voltage Vcom to the common electrode division patterns COM1to COMn during the pixel driving period P1. The touch sensor drivingcircuit 308 may supply a touch driving signal shown in FIG. 5 to thetouch sensing lines S1 to Sn during the touch sensor driving period P2and may sense changes in capacitances of the touch sensors. As shown inFIG. 6, a multiplexer 310 may be installed between the driving circuit308 and the touch sensing lines S1 to Sn, so as to reduce the number ofpins of the driving circuit 308.

The circuitry within the touch sensor driving circuit 308 may also bedivided into different power domains (not shown). A primary power domainincludes circuitry to provide the common voltage Vcom to the sensinglines S1 to Sn lines during the pixel driving period P1. A secondarypower domain includes circuitry to supply touch driving signals to thesensing lines S1 to Sn and to generate touch data during the touchsensor driving period P2. The secondary power domain is powered by asupply voltage VDD or VCC, and the supply voltage VDD or VCC can beselectively cut off to reduce power consumption in the touch sensordriving circuit 308.

The pixel array of the display panel 100 displays an input image. Thepixels of the pixel array are formed in pixel areas defined by the datalines D1 to Dm and the gate lines G1 to Gn in a matrix form. Each pixelis driven by an electric field applied depending on a voltage differencebetween the data voltage applied to the pixel electrode 11 and thecommon voltage Vcom applied to the common electrode, thereby adjusting atransmission amount of incident light. The TFTs are turned on inresponse to a gate pulse from the gate lines G1 to Gn and thus supply adata voltage from the data lines D1 to Dm to the pixel electrodes 11 ofthe liquid crystal cells. The common electrodes receive the commonvoltage Vcom during the pixel driving period P1 and form a referencepotential of the pixels. The common electrode may be divided as shown inFIGS. 3 and 4 and may be used as an electrode of the touch sensor duringthe touch sensor driving period P2.

Black matrixes, color filters, etc. may be formed on a color filtersubstrate of the display panel 100. Polarizing plates are respectivelyattached to the TFT array substrate and the color filter substrate ofthe display panel 100. Alignment layers for setting a pre-tilt angle ofliquid crystals are respectively formed on the inner surfaces contactingthe liquid crystals in the TFT array substrate and the color filtersubstrate of the display panel 100. A column spacer is formed on aliquid crystal layer of the display panel 100 to keep cell gaps of theliquid crystal cells constant.

The display driving circuits 202, 204, and 104 apply data to the pixels.The display driving circuits 202, 204, and 104 include a data drivingcircuit 202, a gate driving circuit 204, and a timing controller 104.

The data driving circuit 202 includes a plurality of source driverintegrated circuits (ICs) SDIC. The source driver ICs SDIC are connectedto the timing controller 104 through EPI (clock embedded) line pairs.The source driver ICs SDIC output an analog video data voltage duringthe pixel driving period P1.

A new signal transmission protocol (hereinafter referred to as “EPIinterface protocol”), which connects the timing controller 104 to thesource driver ICs SDIC in a manner to minimize the number of linesbetween the timing controller 104 and the source driver ICs SDIC and tostabilize the signal transmission, was disclosed in Korean PatentApplication No. 10-2008-0127458 (Dec. 15, 2008), U.S. patent applicationSer. No. 12/543,996 (Aug. 19, 2009), Korean Patent Application No.10-2008-0127456 (Dec. 15, 2008), U.S. patent application Ser. No.12/461,652 (Aug. 19, 2009), Korean Patent Application No.10-2008-0132466 (Dec. 23, 2008), and U.S. patent application Ser. No.12/537,341 (Aug. 7, 2009) owned by the present applicant, and which arehereby incorporated by reference in their entirety.

The EPI interface protocol has the following characteristics (1) to (3).

(1) A transmitting terminal of the timing controller 104 is connected toreceiving terminals of the source driver ICs SDIC via signal line pairs(hereinafter referred to as “EPI line pairs”).

(2) Separate clock line pairs are not connected between the timingcontroller 104 and the source driver ICs SDIC. The timing controller 104transmits a clock signal and digital data to the source driver ICs SDICthrough the EPI line pairs. The digital data includes video data of theinput image and source control data for controlling operations of thesource driver ICs SDIC.

(3) A clock recovery circuit for clock and data recovery (CDR) isembedded in each of the source driver ICs SDIC. The timing controller104 transmits a clock training pattern signal, namely, a preamble signalto the source driver ICs SDIC, so that an output phase and an outputfrequency of the clock recovery circuit can be locked. The clockrecovery circuit embedded in each source driver IC SDIC generates aninternal clock in response to the preamble signal input through the EPIline pairs and locks a phase and a frequency of the internal clock.

When the phase and the frequency of the internal clock are locked, thesource driver ICs SDIC feedback-input a lock signal LOCK of a high logiclevel indicating an output stabilization state to the timing controller104. When the phase and the frequency of the internal clock are stablylocked, a data link, to which the video data of the input image istransmitted, is formed between the source driver ICs SDIC and the timingcontroller 104. After the lock signal LOCK is received from the lastsource driver IC SDIC, the timing controller 104 starts to transmit thevideo data and the control data to the source driver ICs SDIC. When theoutput phase and the output frequency of the clock recovery circuitembedded in any one of the source driver ICs SDIC are unlocked, the locksignal LOCK is inverted to a low logic level. The last source driver ICSDIC transmits the lock signal LOCK of the low logic level to the timingcontroller 104. When the lock signal LOCK is inverted to the low logiclevel, the timing controller 104 transmits the preamble signal to thesource driver ICs SDIC and resumes the clock training of the sourcedriver ICs SDIC.

The source driver ICs SDIC sample and latch digital video data RGBreceived from the timing controller 104 through the EPI line pairsduring the pixel driving period P1. The source driver ICs SDIC convertthe digital video data RGB into positive and negative analog gammacompensation voltages and output the positive and negative data voltagesduring the pixel driving period P1. The positive and negative datavoltages (+/−) (refer to FIG. 7) are supplied to the data lines D1 toDm. The source driver ICs SDIC output the data voltage during a lowlogic period of a source output enable signal SOE. On the other hand,the source driver ICs SDIC do not output the data voltage and mayperform the charge sharing during a high logic period of the sourceoutput enable signal SOE.

The source driver ICs SDIC may perform the clock training in response tothe preamble signal received from the timing controller 104 during thetouch sensor driving period P2.

The gate driving circuit 204 generates a gate pulse (or a scan pulse)synchronized with the data voltage, shifts the gate pulse, andsequentially supplies the gate pulse to the gate lines G1 to Gn underthe control of the timing controller 104 during the pixel driving periodP1. The gate driving circuit 204 is known as a scan driving circuit. Thegate driving circuit 204 includes at least one gate driver IC. The gatedriver IC sequentially supplies the gate pulse synchronized with thedata voltage to the gate lines G1 to Gn under the control of the timingcontroller 104 and selects lines of the display panel 100, to which dataof the input image is applied, during the pixel driving period P1. Thegate pulse swings between a gate high voltage VGH and a gate low voltageVGL as shown in FIG. 7.

The gate driving circuit 204 does not generate the gate pulse and maysupply the gate low voltage VGL to the gate lines G1 to Gn during thetouch sensor driving period P2. Thus, the gate lines G1 to Gn supply thegate pulse to the TFTs of the pixels and sequentially select lines ofthe display panel 100, to which the data of the input image is applied,during the pixel driving period P1. Further, the gate lines G1 to Gn areheld at the gate low voltage VGL and prevents changes in the output ofthe touch sensors during the touch sensor driving period P2.

The timing controller 104 may encode source control data for controllingoperation timing of the data driving circuit 202 using timing signals,such as a vertical sync signal Vsync, a horizontal sync signal Hsync, adata enable signal DE, and a main clock MCLK, received from an externalhost system. The timing controller 104 may transmit the source controldata to the source driver ICs SDIC through the EPI line pairs. Further,the timing controller 104 may transmit a timing control signal forcontrolling operation timing of the gate driving circuit 204 to the gatedriving circuit 204 using the timing signals received from the hostsystem. The timing control signal of the gate driving circuit 204includes a gate start pulse GSP, a gate shift clock GSC, a gate outputenable signal GOE, and the like. The source control data includes apolarity control signal POL, a source output enable signal SOE, optioninformation for controlling output channels of the source driver ICsSDIC, and the like.

The timing controller 104 may compress an external data enable signalreceived from the host system within the previously set pixel drivingperiod P1 and generate an internal data enable signal iDE. The timingcontroller 104 may generate a time-division sync signal Tsync fortime-dividing one frame period into the pixel driving period P1 and thetouch sensor driving period P2 in conformity with the timing of thevertical sync signal Vsync and the internal data enable signal iDE. Thetiming controller 104 may transmit the time-division sync signal Tsyncto a touch controller 306 and may synchronize operations of the displaydriving circuits 202, 204, and 104 with operations of the touch sensordriving circuits 302, 304, 306, and 308.

If the internal data enable signal iDE starts to be generated, thetiming controller 104 may transmit the preamble signal, the controldata, and the data of the input image to the source driver ICs SDIC. Thetiming controller 104 may sequentially transmit the preamble signal, thecontrol data, and the digital video data RGB of the input image to thesource driver ICs SDIC based on the EPI interface protocol during thepixel driving period P1. The timing controller 104 may not transmit anEPI interface signal to the source driver ICs SDIC during the touchsensor driving period P2.

The host system converts the digital video data RGB of the input imageinto a data format suitable to be displayed on the display panel 100.The host system transmits the digital video data RGB of the input imageand the timing signals Vsync, Hsync, DE, and MCLK to the timingcontroller 104. The host system may be implemented as one of atelevision system, a set-top box, a navigation system, a DVD player, aBlu-ray player, a personal computer (PC), a home theater system, and aphone system and receives the input image. The host system runs anapplication associated with touch input coordinates received from thetouch controller 306.

The touch sensor driving circuits 302, 304, 306, and 308 drive the touchsensors and sense the touch input of the touch sensors during the touchsensor driving period P2. The touch sensor driving circuits 302, 304,306, and 308 include the driving circuit 302 (or 308), the sensingcircuit 304, and the touch controller 306. The sensing circuit 304 orthe driving circuit 308 may be integrated into a readout integratedcircuit (IC).

The driving circuit 302 supplies the common voltage Vcom to the Tx linesT1 to Tj during the pixel driving period P1 and supplies a drivingsignal to the Tx lines T1 to Tj during the touch sensor driving periodP2. The driving signal swings between a touch driving voltage Vdry and areference voltage Vref.

The sensing circuit 304 supplies the common voltage Vcom to the Rx linesR1 to Ri during the pixel driving period P1 and receives the voltage ofthe touch sensors during the touch sensor driving period P2. The sensingcircuit 304 amplifies an analog output signal of the touch sensorsreceived through the Rx lines R1 to Ri and converts the amplified analogoutput into digital data. The sensing circuit 304 then generates touchraw data.

The driving circuit 308 of FIG. 4 supplies the common voltage Vcom tothe common electrode division patterns COM1 to COMn during the pixeldriving period P1 and supplies the driving signal shown in FIG. 5 to thesensing lines S1 to Sn during the touch sensor driving period P2. Thedriving circuit 308 then senses changes in capacitances of the touchsensors and outputs the touch raw data.

The touch controller 306 analyzes the touch raw data received from thesensing circuit 304 or the driving circuit 308 using a predeterminedtouch recognition algorithm. In one aspect, the touch controller 306compares the touch raw data with a predetermined threshold voltage fordetecting a touch. For example, the touch controller 306 may use thetouch raw data equal to or greater than the predetermined thresholdvoltage as touch input data and may calculate a touch input position(e.g., coordinates XY) of the touch input data. Information on thecoordinates XY of the touch input position output from the touchcontroller 306 is transmitted to the host system.

The source driver ICs SDIC (corresponding to driver 202) do not need tooperate during the touch sensor driving period P2 and thus are not usedduring the touch sensor driving period P2. On the other hand, thereadout IC (corresponding to 304 or 308) does not need to operate duringthe pixel driving period P1 and thus is not used during the pixeldriving period P1. The related art had the problem of an increase inpower consumption resulting from unnecessary current when driving poweris continuously supplied to each of the source driver IC and the readoutIC during operation of the touch sensing device.

On the other hand, the touch sensing device according to the embodimentof the invention includes a driving power controller (‘400’ of FIG. 13and ‘80’ of FIG. 14) that blocks the driving power from being suppliedto the readout IC during the pixel driving period P1 and blocks thedriving power from being supplied to the source driver ICs SDIC duringthe touch sensor driving period P2. Hence, the embodiment of theinvention prevents unnecessary current from flowing in the readout ICand the source driver ICs SDIC and prevents the power leak.

FIG. 8 illustrates a concept for reducing power consumption of thetime-division driving type touch sensing device according to theembodiment of the invention.

A display operates by dividing a frame period into two distinct periodsof time: a pixel driving period P1 and a touch sensor driving period P1.A driving power controller according to the embodiment of the inventioncuts off the supply voltage applied to the readout IC ROIC during thepixel driving period P1, thereby shutting down at least a portion of thereadout IC ROIC during the pixel driving period P1. Further, the drivingpower controller cuts off the supply voltage applied to the sourcedriver ICs SDIC during the touch sensor driving period P2, therebyshutting down at least a portion of the source driver ICs SDIC duringthe touch sensor driving period P2. Hence, the embodiment of theinvention may prevent unnecessary current from flowing in the readout ICROIC and the source driver ICs SDIC and may prevent the power leak.

The embodiment of the invention does not separately generate a signalfor controlling the driving power and uses the time-division sync signalTsync and the EPI interface signal, which have been already provided bythe touch sensing device, thereby minimizing a cost increase resultingfrom the application of the invention. The driving power controlleraccording to the embodiment of the invention may control the drivingpower of the readout IC ROIC based on the time-division sync signalTsync and may control the driving power of the source driver ICs SDICbased on the EPI interface signal. The embodiment of the inventiondifferentiates between driving power control channels of the readout ICROIC and the source driver ICs SDIC and thus can easily secure a stableoperation.

FIGS. 9 to 12 show the EPI interface signal, to which a driving powercontrol signal is encoded. More specifically, FIG. 9 shows EPI lines EPIconnected between the timing controller 104 and the source driver ICsSDIC#1 to SDIC#8. FIG. 10 shows the timing controller 104 and a clockrecovery circuit of the source driver IC. FIG. 11 is a waveform diagramshowing an EPI interface protocol for signal transmission between thetiming controller 104 and the source driver ICs SDIC#1 to SDIC#8. FIG.12 is a waveform diagram showing the EPI interface signal transmitted tothe source driver ICs SDIC#1 to SDIC#8 during a horizontal blank period.

In FIG. 9, the solid line denotes EPI line pairs EPI, over which signalsincluding the preamble signal, the control data, the video data of theinput image, etc. are transmitted. The dotted line denotes lock linesLCS1 and LCS2, to which a lock signal LOCK is transmitted.

Referring to FIGS. 9 to 12, the timing controller 104 is connected inseries to each of the source driver ICs SDIC#1 to SDIC#8 through the EPIline pairs EPI.

The timing controller 104 sequentially transmits the EPI signalsincluding the preamble signal, the control data, and the video data ofthe input image in the order named to the source driver ICs SDIC#1 toSDIC#8 through the EPI line pairs EPI during the pixel driving periodP1. A control data packet is transmitted as a bit stream including clockbit, control start bit CTR_Start, source control data, gate controldata, etc. A video data packet is transmitted as a bit stream includingclock bit, internal data enable bit, RGB data bit, etc. Each of thesource driver ICs SDIC#1 to SDIC#8 recovers an internal clock signalthat is input through the EPI line pair EPI.

In a first stage Phase-I (see FIG. 11), the timing controller 104transmits a lock start signal to the first source driver IC SDIC#1through the lock line LCS1 and transmits the preamble signal for clocktraining to the source driver ICs SDIC#1 to SDIC#8 through the EPI linepairs EPI. The first source driver IC SDIC#1 generates a lock signalLOCK of the high logic level when a phase and a frequency of theinternal clock are locked and a CRD (clock and data recovery) functionis stabilized, and transmits the lock signal LOCK of the high logiclevel to the second source driver IC SDIC#2. Each of the source driverICs SDIC#2 to SDIC#8 sequentially generates an internal clock throughthe clock training based on the lock signal LOCK of the high logic leveland the preamble signal from a previous source driver IC. Each of thesource driver ICs SDIC#2 to SDIC#7 transmits the lock signal LOCK of thehigh logic level to a next source driver IC when a phase and a frequencyof the internal clock are locked and a CDR (clock and data recovery)function of the corresponding source driver IC is stabilized. When theCDR functions of all of the source driver ICs SDIC#1 to SDIC#8 arestabilized, the last source driver IC SDIC#8 transmits the lock signalLOCK of the high logic level to the timing controller 104 through thelock feedback signal line LCS2. A lock signal input terminal of thefirst source driver IC SDIC#1 is not connected to the output of anyprevious source driver IC. Instead, in one example, a DC power voltageVcc of a high logic level is input to the lock signal input terminal ofthe first source driver IC SDIC#1.

After the timing controller 104 receives the lock signal LOCK of thehigh logic level from the last source driver IC SDIC#8, the timingcontroller 104 transmits the control data and the video data to each ofthe source driver ICs SDIC#1 to SDIC#8 in second and third stagesPhase-II and Phase-III. The control data includes source control datafor controlling output timing, a polarity, etc. of the data voltageoutput from the source driver ICs SDIC#1 to SDIC#8. The control data mayinclude gate control data for controlling operating timing of the gatedriver IC.

The timing controller 104 receives the digital video data RGB of theinput image from the host system through an interface receiving circuit21 (see FIG. 10). The timing controller 104 may generate the controldata including the source control data and the gate control data basedon an external timing signal input from the host system using aninternal timing control signal generating circuit 22. An encoder 23 mayembed clocks CLK, a shut-down control signal SHD, and a wake-up controlsignal WUC in a data packet in conformity with a format determined bythe EPI interface protocol. An output of the encoder 23 is convertedinto differential signal pair through a transmitting buffer 24 and istransmitted to the source driver ICs SDIC#1 to SDIC#8.

A receiving buffer 25 of the source driver IC SDIC receives an EPIsignal from the timing controller 104 through the EPI line pair EPI. Aclock recovery circuit 26 of the source driver IC SDIC recovers thereceived clock and generates an internal clock. A sampling circuit 27 ofthe source driver IC SDIC samples each of bits of the control data andthe digital video data of the input image in conformity with internalclock timing.

In FIG. 11, “Tlock” is a time from after the preamble signal starts tobe transmitted to the source driver ICs SDIC#1 to SDIC#8, until outputsof the clock recovery circuits of the source driver ICs SDIC#1 to SDIC#8are stably locked and the lock signal LOCK is inverted to a high logiclevel H.

In the EPI interface protocol, 1 data packet transmitted to the sourcedriver ICs SDIC#1 to SDIC#8 includes a plurality of data bits and clockbits assigned before and after the data bits. The data bits are bits ofthe control data or bits of the digital video data of the input imageand may include the shut-down control signal SHD and the wake-up controlsignal WUC.

In the EPI interface protocol, as shown in FIG. 12, the signal in thefirst stage Phase-I and the signal in the second stage Phase-II may betransmitted to the source driver ICs SDIC#1 to SDIC#8 in each horizontalblank period between pulses of the internal data enable signal iDE.

FIG. 13 shows a first driving power controller 400 for controlling thedriving power of the readout IC ROIC.

Referring to FIG. 13, the touch controller 306 may communicate with thereadout IC ROIC through a serial peripheral interface (SPI) manner andmay exchange information. The touch controller 306 receives thetime-division sync signal Tsync from the timing controller 104 andsupplies the time-division sync signal Tsync to the first driving powercontroller 400. As shown in FIG. 8, the time-division sync signal Tsyncmay have a first logic level in the pixel driving period P1 and may havea second logic level in the touch sensor driving period P2. When thetime-division sync signal Tsync of the first logic level is input (i.e.,during the pixel driving period P1), the first driving power controller400 cuts off driving supply voltages VCC and VDD applied to the readoutIC ROIC. Hence, at least a portion of the readout IC ROIC is shut downduring the pixel driving period P1, and unnecessary power consumption inthe pixel driving period P1 decreases. When the time-division syncsignal Tsync of the second logic level is input (i.e., during the touchsensor driving period P2), the first driving power controller 400normally applies the driving supply voltages VCC and VDD to the readoutIC ROIC.

In FIG. 13, “VCC” indicates the driving supply voltage applied to andpowering digital circuit blocks of the readout IC ROIC for sensing thetouch input, “VDD” indicates the driving supply voltage applied to andpowering analog circuit blocks of the readout IC ROIC for sensing thetouch input. The first driving power controller 400 may control at leastone of the driving supply voltages VCC and VDD.

FIG. 14 shows a second driving power controller 80 for controlling thedriving power of the source driver IC SDIC. FIG. 15 shows an examplewhere a driving power control signal is encoded to an EPI data packet.

The source driver IC SDIC supplies the positive and negative datavoltages to k data lines D1 to Dk, where k is a positive integer equalto or greater than 2. As shown in FIG. 14, the source driver IC SDIC mayinclude a data sampler and deserializer 71, a digital-to-analogconverter (DAC) 72, an output circuit 73, and the like.

As shown in FIG. 10, the data sampler and deserializer 71 may includethe receiving buffer 25, the clock recovery circuit 26, and the samplingcircuit 27. The data sampler and deserializer 71 outputs the internalclocks using the clock recovery circuit 26 and samples the bits of thedigital video data RGB of the input image received through the EPI linepair EPI in response to the internal clocks. The data sampling anddeserializer 71 latches the sampled data bits and then outputssimultaneously the data bits. Hence, the data bits are converted intoparallel data.

The data sampler and deserializer 71 recovers the control data receivedthrough the EPI line pair EPI in a code mapping manner and generates thesource control data. When the gate control data is encoded to thecontrol data, the data sampler and deserializer 71 recovers the gatecontrol data from the control data received through the EPI line pairEPI and transmits the recovered gate control data to the gate driverICs. The source control data may include the source output enable signalSOE, the polarity control signal POL, the option information, and thelike. The polarity control signal POL indicates polarities of thepositive and negative analog data voltages supplied to the data lines D1to Dk. The source control data and the gate control data are encoded bythe timing controller 104 and are transmitted to the source driver ICSDIC through the EPI line pair EPI in the second stage Phase-II. Anencoding method and a recovery method of the control data in the EPIinterface protocol are disclosed in Korean Patent Application No.10-2008-0132466 (Dec. 23, 2008) and U.S. patent application Ser. No.12/537,341 (Aug. 7, 2009) owned by the present applicant, and which arehereby incorporated by reference in their entirety.

The DAC 72 converts the video data received from the data sampling anddeserializer 71 into a positive gamma compensation voltage GH and anegative gamma compensation voltage GL and generates the positive andnegative analog data voltages. The DAC 72 inverts the polarity of thedata voltage in response to the polarity control signal POL.

The output circuit 73 does not output the data voltage during a highlogic period of the source output enable signal SOE and supplies anaverage voltage of the positive data voltage and the negative datavoltage to the data lines D1 to Dk through the charge sharing. During aperiod of the charge sharing, output channels of the source driver ICsSDIC#1 to SDIC#8, to which the positive data voltage is supplied, andoutput channels of the source driver ICs SDIC#1 to SDIC#8, to which thenegative data voltage is supplied, are short-circuited, and thus theaverage voltage of the positive data voltage and the negative datavoltage is supplied to the data lines D1 to Dk. The output circuit 73supplies the positive and negative data voltages to the data lines D1 toDk through an output buffer during a low logic period of the sourceoutput enable signal SOE. Thus, the source driver IC SDIC outputs thedata voltage during the low logic period of the source output enablesignal SOE and inverts the polarity of the data voltage in response tothe polarity control signal POL.

The timing controller 104 may additionally generate dummy data enablepulses 14 and 16 at the end and the beginning of the pixel drivingperiod P1, respectively, and may transmit the driving power controlsignals SHD and WUC to the source driver IC SDIC through the EPI linepair EPI in synchronization with the dummy data enable pulses 14 and 16.In this instance, as shown in FIG. 15, the driving power control signalsSHD and WUC are encoded inside dummy data packets 15 and 17, that areadditionally generated at the end and the beginning of the pixel drivingperiod P1, respectively, and are transmitted to the source driver ICSDIC.

The data sampling and deserializer 71 recovers the driving power controlsignals SHD and WUC received through the EPI line pair EPI and suppliesthe recovered driving power control signals SHD and WUC to the seconddriving power controller 80.

The second driving power controller 80 cuts off the driving power supplyvoltages VCC and VDD applied to the source driver IC SDIC (i.e., theoutput circuit 73) in response to the shut-down control signal SHDreceived from the data sampling and deserializer 71 during the touchsensor driving period P2. As shown in FIG. 14, the supply voltages VCCand VDD are only cut off to output circuit 73 and are not cut off to theDAC 72. Hence, at least a portion of the source driver IC SDIC is shutdown during the touch sensor driving period P2, and unnecessary powerconsumption in the touch sensor driving period P2 decreases. The seconddriving power controller 80 normally applies the driving supply voltagesVCC and VDD to the source driver IC SDIC in response to the wake-upcontrol signal WUC received from the data sampling and deserializer 71during the pixel driving period P1.

In FIG. 14, “VCC” indicates the driving supply voltage applied to andpowering digital circuit blocks of the source driver IC SDIC, “VDD”indicates the driving supply voltage applied to and powering analogcircuit blocks of the source driver IC SDIC. The second driving powercontroller 80 may control at least one of the driving supply voltagesVCC and VDD.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the scope of the principles of thisdisclosure. More particularly, various variations and modifications arepossible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A power controller for a touch sensing display device supporting a pixel driving period and a touch driving period in each frame period, the display device comprising a data driving circuit to drive data signals onto data lines of a display panel during the pixel driving period of each frame period and being powered by a power supply voltage VDD or VCC, the power controller comprising: a power control circuit to cut off the power supply voltage VDD or VCC from powering the data driving circuit during the touch driving period of each frame period, touch data being generated from signals of touch sensing lines of the display panel during the touch driving period.
 2. The power controller of claim 1, wherein the power control circuit cuts off the power supply voltage VDD or VCC powering the data driving circuit responsive to a shut down control signal provided by a timing controller.
 3. The power controller of claim 2, wherein the power control circuit applies the power supply voltage VDD or VCC powering the data driving circuit responsive to a wake up signal provided by the timing controller.
 4. The power controller of claim 1, wherein the power supply voltage VDD or VCC that is cut off during the touch driving period of each frame period is a power supply voltage for an analog portion of the data driving circuit.
 5. The power controller of claim 1, wherein the power supply voltage VDD or VCC that is cut off during the touch driving period of each frame period is a power supply voltage for a digital portion of the data driving circuit.
 6. The power controller of claim 1, wherein the data driving circuit comprises a digital-to-analog converter (DAC) to convert video data into analog data voltages and an output circuit to drive the analog data voltages onto the data lines, wherein the power supply voltage VDD or VCC that is cut off during the touch driving period of each frame period is cut off to the output circuit but is not cut off to the DAC.
 7. The power controller of claim 1, wherein the touch driving period is distinct from the pixel driving period in each frame period.
 8. A power controller for a touch sensing display device supporting a pixel driving period and a touch driving period in each frame period, the display device comprising a touch readout circuit to generate touch data from signals of touch sensing lines of the display panel during the touch driving period of each frame period, the touch readout circuit powered by a power supply voltage, the power controller comprising: a power control circuit to cut off the power supply voltage from powering the touch readout circuit during the pixel driving period of each frame period, data signals being driven onto data lines of the display panel during the pixel driving period.
 9. The power controller of claim 8, wherein the power control circuit cuts off the power supply voltage of the touch readout circuit responsive to a timing division synchronization signal provided by a timing controller.
 10. The power controller of claim 8, wherein the power supply voltage that is cut off during the pixel driving period of each frame period is a power supply voltage for an analog portion of the touch readout circuit.
 11. The power controller of claim 8, wherein the power supply voltage that is cut off during the pixel driving period of each frame period is a power supply voltage for a digital portion of the touch readout circuit.
 12. The power controller of claim 8, wherein the touch driving period is distinct from the pixel driving period in each frame period.
 13. A method of operation in a power controller for a touch sensing display device driven in a touch driving period and a pixel driving period in each frame period, the method comprising: providing a power supply voltage VDD or VCC to a data driving circuit during the pixel driving period of each frame period, the data driving circuit driving data voltages onto data lines of a display panel during the pixel driving period; and cutting off the power supply voltage VDD or VCC from powering the data driving circuit during the touch driving period of each frame period, touch data being generated from signals of touch sensing lines of the display panel during the touch driving period.
 14. The method of claim 13, wherein the power supply voltage VDD or VCC powering the data driving circuit is cut off responsive to a shut down control signal provided by a timing controller.
 15. The method of claim 14 wherein the power supply voltage VDD or VCC is provided to the data driving circuit responsive to a wake up signal provided by the timing controller.
 16. The method of claim 13, wherein the touch driving period is distinct from the pixel driving period in each frame period.
 17. A method of operation in a power controller for a touch sensing display device driven in a touch driving period and a pixel driving period in each frame period, the method comprising: providing a power supply voltage to a touch readout circuit during the touch driving period of each frame period, the touch readout circuit generating touch data from signals of touch sensing lines of a display panel during the touch driving period of each frame period; and cutting off the power supply voltage from powering the touch readout circuit during the pixel driving period of each frame period, data signals being driven onto data lines of the display panel during the pixel driving period.
 18. The method of claim 17, wherein the power supply voltage of the touch readout circuit is cut off responsive to a timing division synchronization signal provided by a timing controller.
 19. The method of claim 17, wherein the power supply voltage that is cut off during the pixel driving period of each frame period is a power supply voltage for an analog portion of the touch readout circuit.
 20. The method of claim 17, wherein the power supply voltage that is cut off during the pixel driving period of each frame period is a power supply voltage for a digital portion of the touch readout circuit.
 21. The method of claim 17, wherein the touch driving period is distinct from the pixel driving period in each frame period. 